The present invention is in the field of tungsten inert gas or similar type welding torches.
Inert gas shielded welding torches have been in common use for over four decades. These employ a fixed or consummable metal electrode contained within a torch head constructed so that the welding zone is surrounded by a blanket of an inert gas. The gases most normally used are helium and argon. Welding torches of this type are used especially with metals that are highly sensitive to oxidation. Aluminum is perhaps the most common of these metals but the method is critical for more exotic materials such as titanium and zirconium. Similarly, plasma torches employ a jet of extremely hot ionized gas to cause fusion in the weld zone. Once again, it is standard practice for the weld area to be blanketed with an inert gas to prevent oxidation.
In similar fashion to conventional arc welding, inert gas shielded torches employ high electrical currents at relatively low voltages. They tend to be rather small and compact in comparison to the rather bulky welding rod holders used for conventional arc welding.
Tungsten inert gas welding torches most typically have a metallic head portion with a side arm attached to the head at approximately a right angle. Very frequently the head will be water cooled. Water inlet and return lines as well as an inert gas supply line are usually contained within the side arm. These lines further act as an electrical conductor to the tungsten electrode held within the head. Both the head and side arms are covered with an electrical and thermal insulating material which is usually a molded phenolic resin or silicone rubber compound. The side arm serves as a handle to hold the torch when in use.
The tungsten electrode is usually held in the head by a collet-type arrangement. A heat resistant gas cup may extend from the head around the electrode. This serves to place the active tip of the electrode at some distance from the body portion of the head so that the welder has better visibility of the weld zone. Gas cups are usually made of a heat resistant ceramic material such as silicon carbide or aluminum oxide. They are secured to the head by a number of arrangements but almost invariably have been fixed in position relative to the head. With but rare exceptions, the end of the gas cup adjacent to weld zone is formed normal to it's longitudinal axis.
As exemplary of prior art welding torches the following United States patents can be mentioned. Hill, in U.S. Pat. Nos. 4,309,588 and 3,180,967, shows tungsten inert gas welding torches in which the gas cup is threaded to the head portion. Anderson, in U.S. Pat. No. 2,512,706, shows a nozzle or gas cup which is held frictionally in a fixed position on the torch head. Reeh, in U.S. Pat. No. 3,548,143, shows a gas cup held on by a retaining nut. The gas cup in Reeh is elongated and has a lateral orifice for welding in places that might otherwise be inaccessable. Klasson, in U.S. Pat. No. 3,794,806, and Sanders et al., in U.S. Pat. No. 3,909,585, show other examples of torches having threaded ceramic gas cups.
Ideally the gas cup serves to deliver a uniform and nonturbulent flow of gas around the weld area. The problem of turbulence within the shielding gas has been poorly recognized and has received little attention. Dahlman et al., in U.S. Pat. No. 3,521,023, show a pack of stacked spaced apart screens at the nozzle area of a plasma torch. This is described as a "gas lens" whose function is said to be diffusion of the inert gas. The Dahlman torch does not employ a gas cup as do all of the previously noted torches. The aforementioned patent to Hill, U.S. Pat. No. 3,180,967, similarly employs a stacked screen pack at various locations in the nozzle portion to establish coherent streaming of the shielding gas for some distance beyond the immediate mouth of the nozzle.
As noted before, the prior art employs gas cups which are in fixed position on the nozzle. This sometimes results in inconvenience to the welder who must often work in situations where the geometry of the materials being welded makes access difficult. At times a shorter or longer nozzle would be useful while at other times it would be convenient to hold the torch at some oblique angle relative to the weld zone. Further, the rigid nozzle or gas cup portion of the torch tends to be relatively fragile and is occasionally broken by unavoidable impacts encountered in the environment in which a welder must work. These are real problems which a welder faces on a day-to-day basis but heretofore they have not been significantly addressed in the prior art.